Control for refrigerated trucks



ug. 8, 1950 l c. F. Hl-:NNEY i 2,518,316`

CONTROL FOR REFRIGERATED TRCKS Aug. 8, 1950 c. F. HENNEY 2,518,316

CONTROL FOR REFRIGERATED TRUCKS Filed March 23, 1946 5 Sheets-Sheet 2 BYMWQQW.'

Au8- 8, 1950 c. F. HENNEY 2,518,316

coN'rRoL Foa REFRIGERATED TRUCKS Filed March 23, 1946 3 Sheets-Sheet 5 s 40 d f f-/59 IN VEN TOR.

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Patented Aug. 8, 1950 CONTROL FOR REFRIGERATED TRUCKS Charles F. Henney, Dayton, Ohio, assignor to General Motors Corporation, Dayton,

corporation oi' Delaware Application March 23, 1946, Serial No. 656,754

' 7 Claims. (Cl. 62-4) This invention relates to refrigerating apparatus and more particularly to an improved arrangement for refrigerating trucks and the like.

One object of this invention is to provide an 1mproved` arrangement for supplying power for operating a refrigerant compressor.

Another object of this invention is to provide an improved control arrangement for the compressor operating mechanism.

Still another object ofthis invention is to provide a. refrigerating system capable of'refrigerating a plurality of storage compartments each requiring a different temperature.

A still further object of this invention is to provide. an improved arrangement for providing stand-by operation.

A further object of this invention is to provide a system in which power from a common source is utilized for operating both the refrigerant compressor and the air circulating means and in which means is provided for automatically discontinuing operation of the compressor without discontinuing the operation of the air circulating means.

Further 4 advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention isvclearly shown.

In the drawings:

Fig. l shows an elevational view of a refrigerated truck embodying my invention;

Fig. 2 diagrammatically shows the power transmitting mechanism and the refrigeration circuit;

Fig, 3 diagrammatically shows a slightly modied power transmitting mechanism;

Fig. 4 is a fragmentary vertical sectional lview taken on line 4-4 of Fig. 5 showing a modified air distributingarrangement for use within a refrigerated truck; y

Fig. 5 is a horizontal sectional view taken substantially on line 5-5 of Fig. 4;

Fig. 6 is a fragmentary sectional view taken `substantially on line 6--6 of Fig. 5; and

Fig. 'I is '9, fragmentary vertical sectional view taken substantially on line 1--1 of Fig. 6.

Referring now to Fig. 1 of the drawing, there is shown a refrigerated truck having a storage compartment I0, drivers cab section I2, an en- Ohio, a

connected to a drive shaft through a centrifugal clutch 22 of the type which serves to declutch the compressor I8 when the speed of the shaft 20 falls below a given speed and to connect the compressor I8 to shaft 20 when the `speed of the shaft increases above a predetermined speed.

The shaft 20 may be operated either by the hydraulic motor 24 or the stand-by electric motor 26. 'I'he rotor of a condenser blower 28 is directly mounted on the shaft 20 and serves to circulate outside air into the housing I 6 through the inlet 30 and to blow the air over the condenser 32 located directly within the air outlet opening 34 provided in the wall of the housing I6 as shown, 'I'he rotor of an evaporator blower 3B is also mounted directly on the shaft 20 and serves to circulate air to be conditioned in thergine compartment I4, and an air conditioning housing I6 which, for purposes of illustration, has been shown mounted directly beneath the storage compartment` I0. Within the housing I6 there is mounted a refrigerant compressor I8 il? mal exchange with the refrigerant evaporator 38. The inlet duct of the evaporator blower 36 is connected to the return air inlet 42 disposed adjacent the floor of the storage compartment I0 as shown in Fig. l.

In the construction shown in Fig. 1, the air leaving the evaporator 38 is discharged upwardly through the air distributing duct 44 which leadsV to the conditioned air distributor 46 arranged adjacent the ceiling of the storage compartment I0. The arrangement of the air inlets and air outlets within the compartment I0 may be varied considerably without departing from the spirit of my invention.

The compressorl discharges compressed refrigerant into the condenser 32 through the refrigerant line 50. Condensed refrigerant leaves the condenser 32 through the liquid line 52 within which there is provided a conventional refrigerant ow control device 54 which may be a thermostatic expansion valve, a fixed restrictor, or any other type of control device. The vaporized refrigerant leaves the evaporator 38 through the low pressure vapor line 56 which leads to the` compressor I8.

'I'he hydraulic pump 60 is adapted to be driven by the main truck engine VB2 bymeans of the belt 64 or any equivalent powery transmitting mechanism. A manually operated clutch 66 is interior of motor 24.

', shaft thereof in order to vary the stroke of the pistons and consequently the volume of fluid pumped thereby is also conventional and wellknown to those skilled in the art. For example.

such an arrangement is shown and described in the Milton E. Hanson Patent No. 2,104,696 dated January 4, 1938.

In the present disclosure the pump 60 is of the type adapted to deliver a constant volume of liquid to motor 24 irrespective of changes in speed of the main engine 62. 'Ihe stroke controlling wobble or guide plate 12 of pump 60 is connected to the drive shaft 10 thereof by means of a conventional universal connection indicated at 14. Pump 60 is provided with a speed responsive ily ball governor device 16 which has an arm 1| secured to a portion of the device -16 sur-- rounding and being. .movable longitudinally along shaft 10. 'I'he bent end part of arm 1| may bear against or be attached to a box or ring indiv cated at 13 and within which the wobble or guide plate 12' rotates. The fly ball governor 16 operates in response to the speed of the pump shaft and moves the arm 1| longitudinally along shaft 10 and this arm tilts the box or ring 13 to vary the angular relationship of plate 12 relative to the shaft for changing the stroke of each of the pistons 90. Thus when the engine 62 attains suflicient speed to render the y ball governor 16 effective this governor by virture of changing the stroke of pistons 90, increases or decreases the volume of iluid delivered per revolution of the pump shaft 10 to cause the output of pump- 60 to remain constant.

In order to vary the speed of the compressor I8 so as to balance the output of the compressor with the refrigeration demand orv load, I have provided a thermostatically operated means for varying the speed of the hydraulic motor 24. This thermostatic means comprises a closed fluid system. including an expansible and contractible member such as a bellows 80 or the like, a bulb 82 and a tube connection therebetween. A control rod 8| has its one end attached to a movable portion of bellows 80 and extends to the The thermostat bulb 82 may be mounted directly within the storage compartment i 0 or at any other convenient location where it will be aiected by changes -in Vthe refrigeration requirements of the refrigerating system. The end of rod 8| located within motor 24 is connected to an arm 85 secured to a box or ring indicated at 81 and within which a wobble or guide plate 84 rotates as' is disclosed in the aforementioned Hanson patent. Guide plate 84 is connected to the drive shaft 86 of motor 24 by any suitable or conventional universal joint similar to the manner in which guide plate 12 ofpump 60 is connected to shaft 10. Changes in temperature within storage compartment I0 of the truck, to which bulb 82 is exposed. will cause the uid within thethermostatic system to expand and/or condense and this action of the uid expands and/or contracts the conventional manner.

4 bellows 80. Consequently rod 8| secured to the movable portion of bellows member 80 will be moved. Movement of rod 8| shifts arm 85 and consequently box or ring 81 to which it is secured is tilted to thereby change the angular relationship of guide plate 84 relative to shaft 86. Changes in the angularity of wobble or guide plate 84 increases or decreases the stroke of the piston 90 of motor 24 and consequently the speed of the motor. 'I'he guide plates 12vand 84 are each connected to four pistons 90 which are uniformly spaced about the central shaft in the Hydraulic fluid is discharged from the pump 60 through the line 92 which leads to the motor 24 and the uid leaving the motor 24 returns to the pump 60 through the return line 94. 'Ihe construction Vand the l principle of operation of hydraulic motors and pumps of this general type are now well known and need no further description.

Power is transmitted from the motor driven shaft 86 to the shaft 20 by means of the belt |00. A centrifugal clutch |02 is provided for declutching the shaft 20 from the hydraulic motor shaft 86 when it is desired to stop the hydraulic motor 24 and to supply stand-by power by means of the electric motor 26. 'I'his stand-by operation is provided so as to make it possible to refrigerate the storage compartment of the truck when the truck is standing still at the warehouse or at any other location where there is electric power available for operating the motor 26 and it is desired not to operate the truck engine 62. It is to be understood that clutch 22 may cause the compressor I8 to be intermittently stopped and/or started in response to the speed of the hydraulic motor 24 and consequently shaft 20 while the blowers 28x1and 36 operate continuously with operation of motor 24 and shaft 20 to circulate air over the condenser 32 and evaporator 38 irrespective of whether or not compressor I8 is operating.

-In Fig. 3 I have shown a slightly modified arrangement which may be substituted for the arrangement shown in Fig. 2. Like reference numerals have been used to designate like parts iu Figs. 2 and 3. The two arrangements are similar in many respects and both contemplate the use of a hydraulic power transmission. The hydraulic pump |20 shown in Fig. 3 is a conventional pump, the outputy of -which varies in acinlet line |26. A conventional accumulator |30 Y has been provided in the line |24.

A second bypass |32 has been provided, `as shown in Fig. 3, in which there is provided a valve |34 which is controlled by the thermostat |36 located in the conditioned space. As the demand for refrigeration decreases the thermostat |36 serves to open the by-pass valve |34 with the result that less iluid is supplied tothe uid motor |38 which drives the compressor and the blowers. This decrease in fluid causes the motor |38 to operate slower with the result that when no refrigeration is required thespeed of the motor' will have decreased to a point where the clutch 22 win fdeclutch the compresso A| 52 is :accessible from the compartment lThe centrifugal, clutches 22 kand |62 shown in Fig. 3 serve the same purpose as the correspondingly numbered clutches serve-in the arrangement shown in Fig. 2. Thus the motor |38 will operate the blowers at a reduced speedk after the thermostat indicates that no more refrigeration is required and after the clutch 22 has disengaged the compressor. A slightlydiiferentarrangement of blowf ers has-been shown in Fig. 3. Rather than mounting the rotors of the blowers 28 and 36 directly on the shaft 20, as in Fig. 2, they have been mountbe driven through the belt |40. 'I'he blowers 28 and 36 in this. modied showing `also operate to circulate air over the condenser 32 and evaporator 38 `irrespective of whether or not the clutch 22 drivingly connects compressor I8 to shaft 20.

aussie 6 in Fig. 2 or the thermostat |36 of the refrigeration system shown in Fig. 3 would be placed within the compartment |52 so as to maintain that compartment at the desired temperature. The temperature within the compartment |54 may be' controlled by providing a plurality of bailles |80 along the side wal1|16which may be used for covering a portion of the wall |16 at such times when the temperature in the compartment |54 tends to fall below the desired temv perature. A'Ihe `bailles 80 are pivotally mounted ed on a separate shaft |38 and are adapted to delivery truck having three separate compartl ments |50, |52 and |54 arranged to be maintained at different temperatures. The compartment |50 is a non-insulated, non-refrigerated compartment which is accessible through 'the rear door |56. This compartment may be used for 'transporting goods which do not require reair flows through the hollow shelves |58 and t into the two corner ducts |62 provided as shown. in Figs.' 4 and 5. The air ows from the corner ducts |62 into the air space |10 formed above the compartment |54 and returns to the inlet of the evaporator fan through thel air passage |12 formed in the side wall of compartment |54 and from thence returns to the `evaporator through the passage |15 provided in the iloor of the truck. Bailles |14 in the passage |12 improve the air distribution therein. The top and side wall of the compartment |54 are refrigerated in this manner and serve to cool the air in the compartment |54. 1 4

'I'he compartment |54 is accessible through the front door |64 whereas thek center compartment |54 through the inner door |66. The lining |61 of the compartment |54 is made of metal and is preferably spaced and insulated from the outer metal' wall of the truck body so as to facilitate transfer of heat from the cool air'in passage |12 to all portions of the interior of compartment |54.

The same type of refrigeration apparatus may be used for cooling the multiple compartment truck shown in Figs. 4 through 7 as is used cooling the single compartment truck shown in Fig. 1. The refrigeration systems disclosed herein are designed for use in refrigerating either type rof truck.

In order to control the temperature within the llow temperature compartment |52, the refrigeraby means of a series of stationary mounting lugs |82 and are connected together by the main operating rod 84 so as to operate in unison. 'Ihe operating rod |84 is controlled by the expans'ible bellows |86 which in turn is controlled by the thermostat |90 located within the compartment |54. The bailles |80 are preferably formed of insulating material so` as to better `prevent the transfer of heat from the wall |16 to the air within the compartment |54 when the baiiles are moved against the wall.

While no means has been shown for controlling the operation of the stand-by motors 26, it is obvious that these motors may be controlled either manually or automatically so as to maintain suitable temperatures -within the refrigerated compartments during stand-by operation.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the storage compartment, torque transmitting means between said motor and said compressor, and means operable in response to temperatures within said food compartment and acting directly on said hydraulic motor for varying the speed of operation thereofA in accordance with refrigeration requirements of said evaporator.

`2. In combination, a vehicle having means forminga food storage compartment therein and a closed refrigerating system carried thereby, a prime mover for driving said vehicle, Va hydraulic pump operated by said prime mover, means for I maintaining theoutput of said pump substantially constant, a variable speed hydraulic motor operatively connected to said pump, said refrigerating system including a compressor, a condenser and an evaporator for cooling said food storage compartment, torque transmitting means between said motor and said compressor, means operable in response to temperatures within said food compartment for varying the speed of operation of said hydraulic motor, and means actuated automatically in response to the speed of said hydraulic motor for starting and/or stopping operation of said compressor.

3. In combination, a vehicle having means forming a food storage compartment therein and a. closed refrigerating system carried thereby, a prime mover for driving said vehicle, a hydraulic pump operated by said prime mover, means for maintaining the output tiaily constant, a variable speed hydraulic motor operatively' connected to said pump. said refrigerating system including a compressor, a condenser element and an evaporator element for cooling said food compartment, means for circuof said pump substanlating air over one of said elements, torque transmitting `means drivingly connecting said air circulating means and said mpressor to said hydraulic motor, means operable in response to temperatures within said food compartment for varying the speei of operation of said hydraulic motor, and means independent of said air circulating means actuated automatically in response to the speed of said hydraulic motor for starting and/or stopping operation of said compressorl 4. In combination, a vehicle having means forming a food storage compartment therein and a closed refrigerating system carried thereby, a

-erating system including a compressor, a condenser element and an evaporator element for cooling said food compartment, means for circulating air over said condenser element, means for circulating air over said evaporator element, torque transmitting means drivingly connecting both of said air circulating means and said compressorto said hydraulic motor, means operable in response to temperatures within said food compartment for varying the speed of operation of said hydraulic motor, and means independent of both of said air circulating means actuated automatically in response to the speed of said hy(- draulic motor for making and/or breaking the driving connection between said motor and said compressor. Y

5. In combination, a vehicle having means forming a food storage compartment therein and a closed refrigerating system carried thereby, a prime mover for driving said vehicle, a hydraulic pump operated by said prime mover, means for maintaining the output of said pump substantially constant, a variable speed hydraulic motor operatively connected to said pump, said refrig-v erating system including a compressor, a condenser and an evaporator for cooling said food storage compartment, blower means for circulatasians 8 forming a iood storage compartment therein and a closed reirigerating system carried thereby, a prime mover` for driving said vehicle, a hydraulic pump operated by said prime mover, means for maintaining the output oi said pump substantially constant. a variable speed-hydraulic motor operatively connected to said pump. said refrigerating system including a compressor, a'condemer and an evaporator for cooling said food storage compartment, blower means for circulating air over said evaporator and into said food compartment, blower means for circulating air over said condenser, torque transmitting means drivingly connecting said blower means and said compressor to said hydraulic motor, and means operable in response to temperatures within said food compartment acting directly on said hydraulic motor for varying the speed of operation thereof whereby the speed of operation of both oi' said blower means and said compressor is changed in accordance with refrigeration requirements of said evaporator.

7. In combination, a vehicle having means forming a food storage compartment therein and a closed refrigerating system carried thereby, a prime mover for driving said vehicle, a hydraulic pu p operated by said prime mover, means for maintaining the output of said pump substantially constant, a, variable speed hydraulic motor operatively connected to said pump, said refrigerating system including a compressor, a condenser and an evaporator for cooling said food storage compartment, torque transmitting means between said motor and said compressor, means operable in response to temperatures within said iood compartment for controlling the stroke ot said hydraulic motor to vary its speed oi' operation in accordance with refrigeration requirements o! said evaporator, and means actuated automatically in response to the speed of said hydraulic motor for making and/or breaking the driving connection between said motor and said compressor. Y

CHARLES Il'. HENNEY.

REFERENCES CITED le of this patent:

UNITED STATES PATENTS Number Name Date 236,339 Knott Jan. 4, 1881 2,077,974 Wishart Apr. 20, 1937 2,097,857 Ferris et al. Nov. 2, 1937 2,101,495 r Ferris et al. `Dec. 7, 1937 2,104,696 Hanson Jan. 4, 1938 2,180,974 Atchison Nov. 21, 1939 2,212,503 Nickel] Aug. 27, 1940 2,241,701 Doe May 13, 1941 2,257,164 Euwer Sept. 30, 1941 f 2,436,117 Morgan 1 Feb. 17, 1948 Bookman Mar. 9, 1948 

